<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>外边距合并</title>
		<style>
			div#p arent{
				width: 300px;
				height: 300px;
				border: 1px solid red;
				margin-bottom: 90px;
			}
			div#s on{
				width: 100px;
				height: 100px;
				border: 1px solid red;
				margin-top: 100px;
			}
			div#parent{
				width: 300px;
				height: 300px;
				bor der: 1px solid red;
				background-color: #55ff7f;
				margin-top: 98px;
				`overf low: auto;
				border: 1px solid transparent;
				padding-top: 1px;
			}
			div#son{
				width: 100px;
				height: 100px;
				background-color: #55ffff;
				margin-top: 10px;
			}
			
		</style>
	</head>
	<body>
		<div id="parent">
		<div id="son"></div>
		</div>
	</body>
</html>